How can I combine two categorical columns of a tall table?

I have a tall table with two categorical columns -- for example:

    tx = tall(table(categorical({'a';'b';'b';'b'}), categorical({'x';'x';'y';'y'})));

and I want to create a new column that combines those columns.

For regular tables, I would write:

    tx.Var3 = categorical(string(tx.Var1) + " " + string(tx.Var2))

However, this doesn't work with tall tables, since the string.plus method doesn't support tall arrays.

Is there a good way to create this combined column without gathering all the data?

Answer 1

[Edric Ellis]

You can use join, like so:

join([string(tx.Var1), string(tx.Var2)])